Optical keyboard control means with series and parallel light circuits



SEARCH auu nmzwuzz July 7, 1970 R. KOEHN 3,519,116 OPTICAL KEYBOARD CONTROL MEANS WITH SERIES AND PARALLEL LIGHT CIRCUITS Filed May 16. 1968 2 Sheets-$heet l INVENTOR RALPH KOfH/V Arm 4% RiN: P T 5 July 7, 1970 R. KOEHN 3,519,116

OPTICAL KEYBOARD CONTROL MEANS WITH SERIES AND PARALLEL LIGHT CIRCUITS Filed May 16, 1968 2 Sheets-Sheet B FIE-.2-

FIE--5- INYENTOR. FIE-EL RALPH KOEHN BY M W ATTORNE Y5 United States Patent Office 3,519,116 Patented July 7, 1970 3,519,116 OPTICAL KEYBOARD CONTROL MEANS WITH SERIES AND PARALLEL LIGHT CIRCUITS Ralph Koehn, San Francisco, Calif., assiguor to Imagina= tion Designs Engineering and Sales, Inc., San Francisco, Calif., a corporation of California Filed May 16, 1968, Ser. No. 729,807 Int. Cl. B41j /12; G02b 5/14 US. Cl. 197-98 23 Claims ABSTRACT OF THE DISCLOSURE A control system for selective operation of a machine, comprising light conducting circuits, a plurality of movable elements having light conductive and light obstructing sections, each element being operatively movable for conducting or obstructing the passage of light through the circuits; and a keyboard arrangement and mountings for a plurality of keys that may be used in a control system of the type described.

This invention relates to control systems for sequentially and selectively operating a machine. The invention particularly involves a control system that is adapted for operating the printing hammer of a conventional typewriter.

In brief, this invention relates to control systems for sequentially and selectively operating a machine, particularly machines that are operated by keys such as a typewriter. The invention comprises a plurality of control elements having light conductive and light obstructing sections, each element being operatively associated with a pair of light conducting circuits. Each element is normally positioned to conduct light through one of the circuits while obstructing the passage of light through a portion of a second circuit. The control system further comprises means responsive to the passage of light in the first light conducting circuit for illuminating a light source for the second circuit, means for maintaining the illumination of the second light source during an interruption in the passage of light in the first light conducting circuit, and means responsive to the passage of light in a portion of the second light conducting circuit for interrupting the illumination of the second light source and actuating the machine.

The control system specified above may be used with a novel keyboard arrangement also forming a part of this invention. In particular, each of the movable elements or keys is reciprocably mounted in an opening of the keyboard, each key being exposed above a top surface of the keyboard and having engagements with the underside thereof which establish the home position of each key. Means is further provided for adjustably mounting the keyboard relative to a support frame and other means for adjusting the bias with which each key is returned to its home position.

A principal object of this invention is to provide a novel control system for sequentially and selectively operating a machine such as a typewriter.

A second object is to provide a control system of the kind described which may be manufactured with relatively few moving parts as compared with control systems having similar capabilities,

Another object is to provide a control system of the kind described that may be made of relatively low cost materials using many standard parts and conventional manufacturing techniques.

A still further object of this invention is to provide a control system that is particularly suitable for use in the manufacture of a low cost typewriter.

Other objects of this invention will become apparent in view of the following detailed description.

In the drawings forming a part of this application and in which like parts are identified by like reference numerals throughout the same,

FIG. 1 is a schematic diagram of a preferred embodiment of the invention in a control system for operating a typewriter;

FIG. 2 is a vertical section taken through a typewriter and keyboard that embodies the control system of FIG. 1;

FIG. 3 illustrates an intermediate position of key operation in which a key element has been depressed to obstruct the passage of light in both of two light circuits;

FIG. 4 illustrates a position of key operation which completes the normal operation for printing the character of the depressed key; and

FIG. 5 illustrates a position of key operation which conditions the control system for repeatedly printing the character of the depressed key.

Referring to FIGS. 1 and 2 in particular, the control system of this invention comprises a pair of light conducting circuits A and B, each controlled by a plurality of movable elements or keys 10 having three light conductive rods 10a, 10b and inserted in openings of an opaque light obstructing body. It will be seen that each element is operatively movable and each light conducting rod may be positioned for passing light through one of the circuits in a manner which is to be explained in further detail.

More particularly, and with reference to FIG. 2, movable elements 10 are mounted for vertical reciprocation in a sleeve guide 11 mounted to the underside of a support plate 12 forming part of a base frame that is also comprised of a side wall 13 and a base plate 14. Each key element 10 is normally supported in a home position, as shown in; FIG. 2, by a helical spring 15, said spring being seated on a spring guide 16 mounted to a support plate 17. The opposite end of spring 15 engages a ring collar 18, one collar being mounted to the lower end of each key element. A plurality of screw fasteners 19, only one of which is shown, is employed for adjustably mounting plate 17 to base plate 14.

Springs 15- force their respective keys upward until contact is made with the underside of a keyboard 20, said keyboard being vertically adjustable and mounted to support plate 12 of the base frame by a plurality of screw fasteners 21. Peripheral flanges formed on the head of each key engage the underside of the keyboard to establish the home position for each key as it is moved upwardly under the bias of springs 15.

It will be readily seen that the return force of each spring 15 may be adjusted by operation of either screw fastener 19, 21, or both. However, screw fasteners 21 are principally used to make minor adjustments in the home position of the key element 10, screw fasteners 19 then being used to adjust the return force of the springs relative to the setting of the home positions.

Each key element also carries a helical spring 22 on its lower end, one end of the spring being aflixed to the element and the other end projecting downward through an opening in the associated spring guide 16. Springs 22, while normally inoperative, are utilized to impose a bias in addition to the force of springs 15 when the key elements are moved to condition the control system for repeat operations with a single thrust of the key. Under such circumstances, the lower end of springs 22 make contact with base plate 14 as shown in FIG. 5.

It will be noted that the bias imposed by springs 22 will be independent of any position or touch adjustments which are made by rotating screw fasteners 19 and 21.

As indicated above, each key element 10 is operatively s M l associated with a pair of light conducting circuits A and. B. Circuit A comprises a plurality of Plexiglas rods arranged in a series circuit intermediate a light source 26 and a light sensitive photocell 27. Light source 26 is focused upon the end of one rod leading to the first movable element, and the ends of adjacent rods 25 are received in aligned openings of guides 11. The light energy of source 26 will, therefore, be conducted through the entire series circuit whenever a light conducting section of all elements occupies a position between the ends of an associated pair of rods 25. This condition will exist when each of the keys is in its home position as shown in FIG. 2, or when one of the keys is moved to what will be termed the override position, shown in FIG. 5. However, intermediate positioning of any one key between its home position and its override position places a light obstructing section of the element between an aligned pair of rods 25. This condition exists for those intermediate positions of the key elements shown in FIGS. 3 and 4.

Light conducting circuit B comprises a first plurality of Plexiglas rods 28, each rod extending from a second light source 29 to one of the movable elements 10, and a second plurality of Plexiglas rods 30 that extend from one of the movable elements and terminate in front of a timing disc 31, the terminal ends of rods 30 being arranged circumferentially of the disc and directed toward a light sensitive photocell 32. Rods 28 and 30 are received in aligned openings of guides 11 in essentially the same manner as rods 25. Accordingly, light energy will be passed from rods 28 to associated Plexiglas rods 30, but only when a light conductive section of the associated element occupies an intermediate position. This condition exists in the two positions of key actuation shown in FIGS. 4 and 5.

With the foregoing understanding of key construction and operation, attention will be directed to the control system for actuating the printing hammer of a conventional typewriter shown in FIG. 1.

Printing apparatus, particularly typewriters, comprised of a printing disc having a plurality of character pads which may be independently struck against a platen by a printing hammer as the disc is rotated, is now known. The printing hammer of conventional apparatus is actuated by a solenoid which in turn is energized by a timing circuit. FIG. 1 illustrates such an apparatus wherein a disc having a plurality of character pads 35a is rotated by a synchronous motor 36. Character pads 350 are adapted to be struck against a platen roll 37 by the printing hammer 38 as disc 35 rotates. Hammer 38 is normally withdrawn by a spring bias 39 and is actuated in timed relation to the rotation of the disc to strike a selected one of the character pads upon energizing solenoid 40. The energization of solenoid 40, however, is controlled by the timing circuit of the present invention. This circuit is totally different from that of the prior art devices.

More particularly, the timing circuit for the present invention comprises light conducting circuits A and B, including movable elements 10, timer disc 31 having an opening 31a and rotatably driven by synchronous motor 36, light sources 26 and 29, a switching device 42 and a pair of control circuits, one circuit being operated by photocell 27 and the other by photocell 32. Switching device 42 includes a pair of relays 43 and 44 which operate contact arms 43a and 440, respectively.

Relay 43 is energized each time photocell 32 observes a beam of light through the opening 31a of timing disc 31, the output signal of said photocell being amplified by an amplifier 45 connected to the relay. Contact 43a, which is normally open, closes upon energizing relay 43, thereby connecting a power supply 46 to solenoid 40 and to relay 44, opening contact 44a.

Relay 44, it will be seen, controls a pair of power circuits, one of which is energized by photocell 27. This circuit comprises an amplifier 47 which turns on a high voltage supply 48 whenever photocell 27 senses a beam of light in light conducting circuit A. The current from volt age supply 48 is applied to light source 29 through a dropping resistor 49 and a blocking diode 50. A second power source 51 having a relatively low voltage as compared with that of 48 is also provided to supply a current through a blocking diode 52. This power source has only sufficient voltage to maintain the illumination of light source 29. The voltage is insuflicient to start light source 29 after it has been turned off.

The specific control of light source 29 as shown anticipates the use of a neon tube or equivalent apparatus having a relatively high starting voltage, but one which may be sustained by a much lower voltage. It is with this condition in mind that high voltage 48 may be selected with a capacity for turning on light source 29 while power source 51 is selected with a relatively low voltage sutficient to sustain the light source but insufficient to turn it In operation, each of the components of the control system shown in FIGS. 1 and 2 is positioned in what may be regarded as a starting position, each key member 10 being in a home position. It is to be assumed that synchronous motor 36 is in operation and that the timing disc 31 is being rotated synchronously with the printing disc 35. In this condition, light source 26 which is permanently energized, sends a beam of light through the conducting circuit A, including movable elements 10 and Plexiglas rods 25. Accordingly, light energy is sensed by photocell 27, thereby turning on high voltage source 48 and feeding a current through the contact 44a to energize and illuminate light source 29.

Even though light source 29 sends a beam of light energy into Plexiglas rods 28, each element 10 (being in a home position) obstructs the flow of light energy into rods 30. Thus, photocell 32 does not see a light beam from any of the rods 30, and relay 43 remains deenergized.

Upon operating any one of the keys 10, however, the following actions occur: First, as the actuated key reaches the position of FIG. 3, light conducting rod 10a of that member is moved out of alignment between the associated rod 25. In its stead, an opaque portion of the element is placed between the rods as in the position of elements shown in FIG. 3. It will be noted that in such position an opaque portion of the element remains between the associated rods 28 and 30.

Referring now to FIG. 1, it will be seen that the interruption of light through any one of the elements as caused by the movement into the position of FIG. 3 interrupts the passing of light in series circuit A, thereby de-energizing high voltage source 48. But this action has no effect upon low voltage source 51, which then continues to supply a voltage across contact 440 to sustain the illumination of second light source 29. Since each of the elements 10 (including the element actuated to the position of FIG. 3) blocks the passage of light in all terminal connections 30 of light conducting circuit B, no light beam is as yet detected by photocell 32 and, therefore, relay 43 remains de-energized.

The further depression of key 10 to the position of FIG. 4 positions light conducting rod 10b between the rods 28 and 30. Accordingly, a beam of light emanating from light source 29 is now conducted to the terminal end of the associated rod 30; and when disc 31 is positioned such that its opening 31a becomes aligned with the end of rod 30, photocell 32 receives a pulse of light that triggers the energization of relay 43, closing contact 43a to energize both relay 44 and solenoid 40. Relay 44 now opens contact 4411.

Opening contact 44a interrupts the flow of current to second light source 29. Therefore, even though contact 44a may later be closed to conduct current from low voltage source 51 while the actuated key 10 is held in a depressed position, light source 29 cannot be turned on again until high voltage 48 is supplied. This condition will be met only when the light conducting rod 10a, or, alternately, light conducting rod 100, is placed between the associated and aligned rods 25. This control inhibits further operation of solenoid 40 until the key is returned to a home position or unless the key is depressed to the override position shown in FIG. 5a

A second condition for insuring proper actuation of solenoid 40 is that contact 4311 must be closed for a time sufficient to actuate hammer 38. For this purpose, at capacitor 54 may be placed across relay 43. A second capacitor 55 may also be placed across relay 44 to insure proper timing and operation of contact 44a. The value of capacitor 55 is selected to create a delay in the closing of relay contact 44a, thereby allowing hammer 38 to complete its operation before light source 29 can be turned on.

In operations where a particular character is to be repeatedly struck, it is only necessary to depress the selected key into the override position illustrated by FIG. 5. It will be noted that the keys are then positioned such that light conducting circuits A and B are continuously conditioned for passing light energy from the light sources 26 and 29 to the respective photocell controls 27 and 32. Thus, after a single operation and as soon as contact 4 4a closes, light energy will be conducted through light conducting circuit B and received by photocell 32, energizing relay 43, actuating solenoid 40 and energizing relay 44, and breaking contact 44a, in that order. The control system will then continuously repeat the operation so long as the key remains in its override position.

Although switching device 42 has been illustrated and described as a device having electro-mechanical components, it is to be understood that for many applications, especially where speed of switching is essential, electronic switching devices may be preferred. The substitution and use of such devices is expressly contemplated by this invention. Thus, although a single preferred embodiment of this invention has been illustrated and described, various modifications and changes may be made without departing from the spirit of the invention or the scope of the attached claims, and each of such modifications and changes is contemplated.

What is claimed is:

1. A control system for operating a machine comprising: a plurality of control elements, each element having light lconductive and light obstructing sections; a first light source; means defining a light"conducting passageway connecting eachof said elements in series with said first light source, each element being normally positioned to pass light through the passageway'but capable of being moved to interrupt the passage of light therethrough; a second light source; means defining a light conducting circuit connecting said second light source with each of said movable elements, each element being connected in parallel with other elements and normally positioned to obstruct the flow of light emanating from said second light source; means responsive to the passage of light in said light conducting passageway for illuminating said second light source; means for maintaining the illumination of said second light source during an interruption in the passage of light in said light conducting passageway; and means responsive to the passage of light through a light conductive section of any one of said control elements in said light conducting circuit for interrupting the illumination of said second light source.

2. A control system for operating a machine comprising: a plurality of movable elements having light conductive and light obstructing sections; a first light conducting means intermediate a light source and extending to first one and then to other movable elements as to connect each element in series 'with said light source, each element being normally positioned to conduct light through said first light conducting means; a second light conducting means intermediate a second light source and extending to each of said movable elements as to connect each element in parallel with other elements, each element being normally positioned to obstruct the passage of light from said second light source; means responsive to the passage of light in said first light conducting means for illuminating said second light source; means for maintaining the illumination of said second light source during an interruption in the passage of light in said first light conducting means; and means responsive to the passage of light in any one of the parallel portions of said second light conducting means for interrupting the illumination of said second light source.

-3. The control system of claim 2, wherein each movable element is formed with first and second light conductive sections and first and second light obstructing sections, said first light conductive and light obstructing sections being disposed in operative relation to said first light conducting means and said second light conductive and light obstructing sections being disposed in operative relation to said second light conducting means, said first and second light conductive and light obstructing sections being further disposed relative to said first and second light conducting means to conduct light in said first light conducting means while obstructing light in a parallel portion of said second light conducting means.

4. The control system of claim 2, said means for illuminating said second light source comprising a light sensitive control for applying an illuminating current to said second light source.

5. The control system of claim 2, said means for maintaining the illumination of said second light source comprising a secondary power source having a voltage for maintaining the illumination of said second light source but incapable of initiating the illumination thereof.

6. The control system of claim 2, said means for interrupting the illumination of said second light source and actuating said machine comprising an electronic switch normally conditioned for conducting an illuminating current to said second light source, said switch being operated to interrupt the flow of current thereto upon positioning any one of said elements to pass light in one of the parallel portions of said second light conducting means.

7. The control system of claim 2, said means responsive to the passage of light in any one of the parallel portions of said second light conducting means comprising a light sensitive control connected to an electronic switch, said switch being normally conditioned for conducting an illuminating current to said second light source.

8. The control system of claim 2, said second light conducting means comprising a plurality of light conduits, each conduit being focused upon a light sensitive control; and further comprising a timing disc rotatably mounted intermediate said light sensitive control and said plurality of light conduits, said timing disc having an aperture for selectively exposing said light sensitive control with the emission of light from any one of said light conduits.

9. The control system of claim 2, each of said movable elements further including a light conductive section that may be positioned for conducting light through said first light conducting means while said element is also positioned for conducting light in a parallel connection of said second light conducting means.

10. The control system of claim 9 and further comprising a plurality of means for resiliently biasing each of said movable elements, respectively, toward a home position for passing light in said first light conducting means and obstructing light in a parallel connection of said second light conducting means, each of said resilient means comprising a pair of spring members disposed intermediate one element in a support, one spring member of each pair being operative for imposing a bias to return said element to its home position, the other spring member being operative to impose a secondary bias when said element is moved into an override position where light conductive sections thereof pass light in both said first and second light conducting means.

11. The control system of claim 10, and further comprising a control panel for positioning each movable element at its home position, and means for adjusting the position of said control panel relative to said movable elements to vary the length of stroke of said elements without affecting the secondary bias of said second spring member.

12. The control system of claim 10, and further comprising means for adjusting the position of said support relative to said elements to vary the bias of each spring member that tends to return said elements to home positions without affecting the secondary bias of other spring members.

13. The control system of claim 2, each of said movable elements being biased into a home position that conducts light in said first light conducting means and obstructs light in a parallel connection of said second light conducting means.

14. The control system of claim 2, and further comprising a control panel for positioning each movable element at its home position, and means for adjusting the position of said control panel relative to said movable elements.

15. The control system of claim 2, and further comprising a support panel, resilient means disposed between said support panel and each of said elements, respectively, for biasing said elements into home positions; and means for adjusting the position of said support panel relative to said elements to adjust the strength of the bias with which each is returned to its home position.

16. In combination with a typewriter having a rotatable printing disc and means for striking said printing disc to imprint characters carried thereon as said disc is rotated, an improved control system comprising: a plurality of movable keys, each key having light conductive and light obstructing sections; a first light conducting means intermediate a first light source and extending to first one and then to other movable keys as to interconnect each key in series with said light source, each key being normally positioned to conduct light through said first light conducting means; a second light conducting means intermediate a second light source and extending to each of said movable keys as to connect each key in parallel with other keys, each key being normally positioned to obstruct the passage of light from said second light source; means responsive to the passage of light in said first light conducting means for illuminating said second light source; means for maintaining the illumination of said second light source during an interruption in the passage of light in said first light conducting means; and means responsive to the passage of light in any one of the parallel portions of said second light conducting means for actuating the means for striking said printing disc and interrupting the illumination of said second light source.

17. The improvement of claim 16, said second light conducting means comprising a plurality of light conduits, each conduit being focused upon a light sensitive control; and further comprising a timing disc rotatably mounted intermediate said light sensitive control and said plurality of light conduits, said timing disc having an aperture for selectively exposing said light sensitive control with the emission of light from any one of said light conduits.

18. The improvement of claim 16 and further comprising a keyboard, each of said keys being reciprocally mounted in an opening of said keyboard, each key being exposed above the top surface of the keyboard and having engagements with the underside of the keyboard that establish home positions; and means biasing each of said keys, respectively, to return said keys to home positions.

19. The improvement of claim 18, and further comprising a support frame and means for adjustably mounting said keyboard relative to said support frame to vary the actuating throw of said keys.

20. The improvement of claim 18, and further including means for adjusting the bias with which each key is returned to its home position.

21. The improvement of claim 20, and further comprising a plurality of spring members, one member being mounted to the lower end of each key and engageable with said support frame when said key is moved into an override position where light conductive sections pass light in both said first and second conducting means.

22. A, control system for operating a machine comprising a plurality of movable control elements; a first control circuit interconnecting each of said elements in series with a source of energy, each element being normally positioned to transmit energy through the circuit but capable of being moved to interrupt the transmission of energy therethrough; a second control circuit extending from a second energy source to each of said movable elements, each element being connected in parallel with other elements and normally positioned to obstruct the flow of energy from said second energy source; means responsive to the transmission of energy in said first circuit for initiating a flow of energy from said second energy source, means for sustaining the transmission of energy from said second energy source during an interruption in the transmission of energy in said first circuit; and means responsive to the transmission of energy through any one of said control elements in said second circuit for interrupting the transmission of energy from said second energy source.

23. The control system of claim 22, said second control circuit comprising a plurality of light conduits, each conduit being focused upon a light sensitive control; said means responsive to the transmission of energy in said second circuit including a light sensitive control; and further comprising a timing disc rotatably mounted intermediate said light sensitive control and said plurality of light conduits, said timing disc having an aperture for selectively exposing said light sensitive control with the emission of light energy from any one of said light conduits.

References Cited UNITED STATES PATENTS 2,228,780 l/1941 Roberts 197-98 XR 2,408,754 10/1946 Bush 1975 XR 2,438,825 3/1948 Roth l97-98 XR 2,518,726 8/1950 Shlenker 35096 XR 3,017,463 l/l962 Dinsmore et al. 197-98 XR 3,032,163 5/1962 Flieg l97l.5 3,104,388 9/1963 Balenger 19798 XR 3,334,237 8/1967 Dodsworth et al. 197-98 XR 3,365,568 l/1968 Germen 350-96 3,372,789 3/1968 Thiel et al. l97-98 3,465,099 9/1969 Harris 197-98 XR FOREIGN PATENTS 723,793 8/1942 Germany.

OTHER REFERENCES IBM Technical Disclosure Bulletin, vol. 5, No. 10, March 1963, p. 127, article by Sharp et al. entitled Optical Keyboard.

IBM Technical Disclosure, Bulletin, vol. 5, No. 1, June 1962, p. 89, article by Brandenberg entitled Pluggable Fiber Optics Data Searching Apparatus.

EDGAR S. BURR, Primary Examiner 

